Fuel injector mounting construction for engine

ABSTRACT

A fuel injector mounting construction for an engine includes an improved thrust member. The engine is a direct injected, internal combustion engine. A fuel injector is provided for spraying fuel into a combustion chamber and inserted into an opening formed in a cylinder head. The fuel injector has a contact surface for receiving a loading or thrust force. The contact surface extends about the nozzle of the fuel injector. A seal member is provided for sealing a space between the fuel injector and the opening. The thrust member has a fixing section and a thrust section. A fixing member affixes the thrust member onto the cylinder head at the fixing section and thereby loads the thrust section onto the contact surface to exert a upon the contact surface toward the combustion chamber. At least one of the thrust section and the fixing section has a convex surface. The convex surface allows for varying orientations of the thrust member when mounted onto the cylinder head and thereby permits the thrust member to squarely load the contact surface, such that the force is substantially uniform about the contact surface, despite manufacturing tolerance stack-ups.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a fuel injector mounting constructionfor an in internal combustion engine, and more particularly to animproved fuel injector mounting construction on a direct injected enginethat can securely hold a fuel injector notwithstanding manufacturingtolerances.

[0003] 2. Description of Related Art

[0004] In all fields of engine design, there is an increasing emphasison obtaining more effective emission control, better fuel economy and,at the same time, continued high power output. This trend has resultedin the substitution of fuel injection systems for carburetors as theengine charge former. In the common systems used, fuel is injected intoan intake air manifold. In order to obtain still further improvement,direct injection systems are being considered. These systems inject fueldirectly into the combustion chamber and thus have significant potentialadvantages such as fine emission control.

[0005] An injection nozzle of a fuel injector employed in a conventionaldirect injection system is exposed to a combustion chamber through anopening formed in a cylinder head assembly. A forked member usually isused to affix the fuel injector onto the cylinder head assembly. Theforked member is secured to the cylinder head assembly with a fastenersuch as a bolt. Meanwhile, the forked member contacts the body of thefuel injector with its forked section to push a flange of the fuelinjector toward the combustion chamber so that the injection nozzle ofthe fuel injector can be exposed to the combustion chamber.

[0006] The fuel injector often has a mount section between the flangeand the injection nozzle. This mount section has a diameter larger thana diameter of the injection nozzle but smaller than a diameter of theflange.

[0007] The cylinder head opening includes two sections: a small diameteropening section and a large diameter opening sections. A generallysquare step occurs at the transition between the two opening sections.

[0008] The mount section of the fuel injector is seated at this stepportion and loaded by the forked member. A seal member, such as a discspring, conventionally is provided between the mount section of the fuelinjector and the step portion to seal up this area.

[0009] On occasion, the loading on the fuel injector and thus on theseal can be non-uniform around the seal and can be less than a desiredloading. The effectiveness of the seal thus is jeopardized. This occursbecause the configuration of the forked member and the surface of thecylinder head on which it is mounted vary due to manufacturingtolerances. If these tolerances stack-up adversely, the forked memberdoes not squarely load the fuel injector, and thus the loading aroundthe seal is not uniform. At the extreme, the fuel injector can assume anoticeably skewed orientation relative to a central axis of the openingin which is mounted.

[0010] Hot gases and flames can leak through the seal if the fork memberdoes not properly load the fuel injector and compress the seal. That is,if the seal is not uniform and one section of the seal is not properlycompressed, hot gases and flames will leak through the improperly loadedsection of the seal. The injector nozzle consequently is excessivelyheated and deposits can form on the nozzle. These deposits can block andclog the nozzle apertures thereby preventing proper fuel injection andeffecting engine performance and emission control.

SUMMARY OF THE INVENTION

[0011] A need therefore exists for a mounting construction of the fuelinjector that consistently produces an effective seal between fuelinjector and the engine body.

[0012] In accordance with one aspect of the present invention, a directfuel injected, internal combustion engine comprises an engine bodydefining, at least in part, at least one combustion chamber. A fuelinjector is arranged to spray fuel directly into the combustion chamber.The engine body has an opening through which the fuel injector isinserted, and the fuel injector having a contact surface. A thrustmember is arranged to exert a loading onto the contact surface towardthe combustion chamber, and a fixing member affixes the thrust memberonto the engine body. A sealing member is disposed within a spacebetween the fuel injector and the opening. The thrust member includes athrust section contacting the contact surface of the fuel injector and afixing section at which the thrust member is affixed onto the enginebody by the fixing member. At least one of the thrust section and thefixing section having a convex surface.

[0013] The convex surface allows for varying orientations of the thrustmember relative to the engine body when mounted to the engine body. Thethrust member in this manner can squarely load the fuel injector contactsurface such that the applied force is substantially uniform about thecontact surface despite manufacturing tolerance stack-ups. The generallyuniform pressure about the contact surface at a desired loading producesuniform pressure about the sealing member to produce an effective sealbetween the fuel injector and the engine body, thereby inhibitingoverheating of the fuel injector and deposit formations on a fuelinjector nozzle.

[0014] Further aspects, features and advantages of this invention willbecome apparent from the detailed description of the preferredembodiments which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] These and other features of this invention will now be describedwith reference to the drawings of preferred embodiments which areintended to illustrate and not to limit the invention, and which;

[0016]FIG. 1 is a schematic view of an engine which is configured inaccordance with the preferred embodiment of the present invention asemployed on an outboard motor, and illustrates in Sections 1A theoutboard motor from a side elevational view, illustrates in Sections 1Band 1C a partial schematic view of the engine with associated portionsof induction and fuel supply systems, illustrates in Section 1D asectional view of the engine (as taken along line I-I of the Section 1B)and a portion of a driveshaft housing of the outboard motor, andillustrates an electronic control unit (ECU) of an engine control systemcommunicating with various sensors and controlled components of theengine;

[0017]FIG. 2 is a top plan view showing a power head incorporating theengine with the engine shown in solid lines and a protective cowlingshown in phantom;

[0018]FIG. 3 is a schematic perspective view showing components relatingto a high pressure fuel injection assembly exploded from the engine, andis taken generally in the direction of the arrow 3 in FIG. 2;

[0019]FIG. 4 is an elevational view showing a main cylinder head membertaken in the direction of the arrow 4 in FIG. 8, and particularlyillustrates a water flow path in a cooling system employed in theengine;

[0020]FIG. 5 is an elevational and upper partial view showing the samemain cylinder head member taken in the direction of the arrow 5 in FIG.8 and illustrates particularly another section of the water flow path inthe same cooling system;

[0021]FIG. 6 is a cross-sectional view showing the same main cylinderhead member of FIG. 5 taken along the line 6-6 in FIG. 5;

[0022]FIG. 7 is a schematic view generally showing the entire water flowpath in the cooling system;

[0023]FIG. 8 is a cross-sectional plan view showing a preferredembodiment of a mounting construction for a fuel injector onto acylinder head assembly;

[0024]FIG. 9 is an enlarged partial elevational view showing the samemounting construction taken in the direction from the arrow 9 in FIG. 8;

[0025]FIG. 10 is an enlarged partial cross-sectional view showing thesame mounting construction taken along the line 10-10 in FIG. 8;

[0026] FIGS. 11(A) to (C) show a thrust member used for mounting thefuel injector; FIG. 11(A), (B),(C) are a top plan view, a lateral sideview and a longitudinal side view, respectively;

[0027]FIG. 12 is an elevational side view of a bolt of the mountingconstruction;

[0028]FIG. 13 is a cross-sectional plan view showing another preferredembodiment of the mounting construction;

[0029]FIG. 14 is an enlarged partial elevational view showing the samemounting construction taken in the direction from the arrow 14 in FIG.13;

[0030]FIG. 15 is an enlarged elevational view showing and additionalembodiment of the mounting construction; and

[0031]FIG. 16 is a top plan view showing a power head which incorporatesa four stroke engine that can be provided with the embodiment of thepresent invention, with the engine shown in solid lines and a protectivecowling shown in phantom.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0032] The general overall environment in which the invention ispracticed and certain details of the engine will be described primarilywith reference to FIG. 1.

[0033] In FIG. 1A, an outboard motor constructed and operated inaccordance with an embodiment of the invention is depicted in sideelevational view and is identified generally by the reference numeral30.

[0034] The entire outboard motor 30 is not depicted in that the swivelbracket and clamping bracket that are associated with the driveshafthousing, indicated generally by the reference numeral 32, are notillustrated. This is because these components are well known in the artand the specific method by which the outboard motor 30 is mounted to thetransom of an associated watercraft is not necessary to permit thoseskilled in the art to understand or practice the invention.

[0035] The outboard motor 30 includes a power head, indicated generallyby the reference numeral 34, that is positioned above the driveshafthousing 32 and which includes a powering internal combustion engine,indicated generally by the reference numeral 36. This engine 36 is shownin more detail in the remaining two views of this figure and will bedescribed shortly by reference thereto.

[0036] The power head 34 is completed by a protective cowling whichincludes a top cowling member 38 and a bottom cowling 40. This topcowling member 38 is detachably connected to the bottom cowling member40 which is a lower tray portion of the protective cowling and encirclesan upper portion of the driveshaft housing 32, particularly an exhaustguide 42 for an exhaust system of the engine 36.

[0037] The top cowling member 38 has a pair of compartments (not shown)placed at rear and both sides of its body. The compartments openrearward so that air is introduced into these compartments. Air inletbarrels 44 (see FIG. 2), which have no bottom portion, stand in therespective compartments. The air inlet barrels 44 look like a funnel andthe compartments are connected with interior of the top cowling member38 through the air inlet barrel 44. Thus, the air is admitted intointerior of the top cowling member 38 and then goes to an air inductionsystem, indicated generally by the reference numeral 46.

[0038] Positioned beneath the driveshaft housing 32 is a lower unit 48in which a propeller 50, which forms the propulsion device for theassociated watercraft, is journaled.

[0039] As is typical with outboard motor practice, the engine 36 issupported in the power head 34 so that its crankshaft or output shaft 54(see the upper view) rotates about a vertically extending axis. This isdone so as to facilitate connection of the crankshaft 54 to a driveshaft(not shown) which depends into the driveshaft housing 32 and whichdrives the propeller 50 through a conventional forward, neutral, reversetransmission contained in the lower unit 48.

[0040] The details of the construction of the outboard motor 30 and thecomponents which are not illustrated may be considered to beconventional or of any type known to those wishing to utilize theinvention disclosed herein. Those skilled in the art can readily referto any known constructions with which to practice the invention.

[0041] With reference now in detail to the construction of the engine 36still by primary reference to FIG. 1, in the illustrated embodiment, theengine 36 is of the V6 type and operates on a two stroke, crankcasecompression principle. Although the invention is described inconjunction with an engine having this cylinder number and cylinderconfiguration, it will be readily apparent that the invention can beutilized with engines having other cylinder numbers and other cylinderconfigurations.

[0042] Also, although the engine 36 will be described as operating on atwo stroke principle, it will also be apparent to those skilled in theart that almost all facets of the invention can be employed inconjunction with four stroke engines as noted later.

[0043] The engine 36 comprises a cylinder block 56 that is formed with apair of cylinder banks 58. Each of these cylinder banks 58 is formedwith three vertically spaced, horizontally extending cylinder bores 60.Pistons 62 reciprocate in these cylinder bores 60.

[0044] The pistons 62 are, in turn, connected to the upper or small endsof connecting rods 64. The big ends of these connecting rods 64 arejournaled on the throws of the crankshaft 54 in a manner that is wellknown in this art.

[0045] The crankshaft 54 is journaled in a suitable manner for rotationwithin a crankcase chamber 68 that is formed in part by a crankcasemember 70 that is affixed to the cylinder block 56 in a suitable manner.The cylinder block 56 and the crankcase member 70 generally define anengine body. As is typical with two stroke engines, the crankshaft 54and crankcase chamber 68 are formed with seals so that each section ofthe crankcase that is associated with one of the cylinder bores 60 willbe sealed from the others. This type of construction is well known inthe art.

[0046] A cylinder head assembly, indicated generally by the referencenumeral 72, is affixed to the end of the cylinder banks 58 that arespaced from the crankcase chamber 68. These cylinder head assemblies 72are comprised of a main cylinder head member 74 that defines a pluralityof recesses 76 (see FIG. 8) in its lower face. Each of these recesses 76corporate with the respective cylinder bore 60 and the head of thepiston 62 to define the combustion chambers 78 of the engine 36. This isalso well known in the art. A cylinder head cover member 80 completesthe cylinder head assembly 72. The main cylinder head members 74 and thecylinder block 56 are affixed to each other and to the respectivecylinder banks 58 in a suitable, known manner.

[0047] The air induction system 46 is provided for delivering an aircharge to the sections of the crankcase chamber 68 associated with eachof the cylinder bores 60. This communication is via an intake port 82formed in the crankcase member 70 and registering with each suchcrankcase chamber section.

[0048] The induction system 46 includes an air silencing and inletdevice, shown schematically in this figure and indicated by thereference numeral 84. The actual construction of this air charge deviceappears in FIGS. 2. In actual physical location, this device 84 iscontained within the top cowling member 38 at the forward end thereofand has a rearward facing air inlet opening 86 through which air isintroduced.

[0049] The air inlet device 84 supplies the induced air to a pluralityof throttle bodies 88, each of which has a throttle valve 90 providedtherein. These throttle valves 90 are supported on throttle valve shafts(not shown). These throttle valve shafts are linked to each other forsimultaneous opening and closing of the throttle valves 90 in a mannerthat is well known in this art.

[0050] As is also typical in two stroke engine practice, the intakeports 82 have, provided in them, reed-type check valves 92. These checkvalves 92 permit the air to flow into the sections of the crankcasechamber 68 when the pistons 62 are moving upwardly in their respectivecylinder bores. However, as the pistons 62 move downwardly, the chargewill be compressed in the sections of the crankcase chamber 68. At thattime, the reed type check valve 92 will close so as to permit the chargeto be compressed. In addition, lubricant pumps 94 are provided forspraying lubricant into the throttle bodies 88 for engine lubricationunder the control of an ECU (Electronic Control Unit) 96 that will bedescribed more in detail later. Although it is not shown, some forms ofdirect lubrication may be also employed for delivering lubricantdirectly to certain components of the engine.

[0051] The charge which is compressed in the sections of the crankcasechamber 68 is then transferred to the combustion chambers 78 as througha scavenging system (not shown) in a manner that is well known. As bestseen in FIG. 8, spark plug 98 is inserted into an opening 100 formed ata boss 101 for each combustion chamber 78. The spark plug 98, in turn,fire a fuel air charge that is formed by mixing fuel directly with theintake air via a fuel injector 102 in each combustion chamber 78. Thefuel injectors 102 are solenoid type and electrically operated alsounder the control of the ECU 96. The fuel injectors 102 are mounteddirectly in the cylinder head member 74 in a specific location, as willbe described, so as to provide optimum fuel vaporization under allrunning conditions.

[0052] As seen in Figure Sections 1B and 1C, fuel is supplied to thefuel injectors 102 by a fuel supply system, indicated generally by thereference numeral 104. The fuel supply system 104 comprises a main fuelsupply tank 108 that is provided in the hull of the watercraft withwhich the outboard motor 30 is associated. Fuel is drawn from this tank108 through a conduit 110 by means of a first low pressure pump 112 anda plurality of second low pressure pumps 114. The first low pressurepump 112 is a manually operated pump and the second low pressure pumps114 are diaphragm type pumps operated by variations in pressure in thesections of the crankcase chamber 68, and thus provide a relatively lowpressure. A quick disconnect coupling (not shown) is provided in theconduit 110 and also a fuel filter 116 is positioned in the conduit 110at an appropriate location.

[0053] From the low pressure pump 114, fuel is supplied to a vaporseparator 118 which is mounted on the engine 36 or within the topcowling member 38 at an appropriate location. This fuel is suppliedthrough a line 120. At the vapor separator end of the line 120, there isprovided at a float valve (not shown) that is operated by a float 122 soas to maintain a uniform level of fuel in the vapor separator 118.

[0054] A high pressure electric fuel pump 124 is provided in the vaporseparator 118 and pressurizes fuel that is delivered through a fuelsupply line 126 to a high pressure pumping apparatus, indicatedgenerally by the reference numeral 128. The electric fuel pump 124,which is driven by an electric motor, develops a pressure such as 3 to10 kg/cm². A low pressure regulator 130 is positioned in the fuel supplyline 126 at the vapor separator 118 and limits the pressure that isdelivered to the high pressure pumping apparatus 128 by dumping the fuelback to the vapor separator 118.

[0055] The high pressure fuel pump 128 that can develop a pressure of,for example, 50 to 100 kg/cm² or more. A pump drive unit 132 (the lowerleft hand view) is provided for driving the high pressure fuel pump 128.

[0056] With reference primarily to FIGS. 2 and 3, the high pressure fuelpump 128 is mounted on the pump drive unit 132 with bolts 134. A stay138 is affixed to the cylinder block 56 at a boss 140 with a bolt 142and at a boss 144 with a bolt 146. Then, the pump drive unit 132 isaffixed to the stay 138 at a bolt hole 148 with a bolt 150 and at bolthole 152 with a bolt 154. The pump drive unit 132 is, further, affixedto the cylinder block 56 directly at a boss 156 with a bolt 158. Thus,the pump drive unit 132 overhangs between the two banks 58 of the Varrangement. A pulley 160 is affixed to a pump drive shaft 162 of thepump drive unit 132. The pulley 160 is driven by a drive pulley 164affixed to the crankshaft 54 by means of a drive belt 166. The pumpdrive shaft 162 is provided with a cam disc 168 existing horizontallyfor pushing plungers (not shown) which are disposed on the high pressurefuel pump 128.

[0057] The high pressure fuel pump 128 has a unified fuel inlet andoutlet module 170 which is mounted on a side wall of the pressure pump128. The inlet and outlet module 170 has an inlet passage (not shown)connected to the fuel supply line 126 with a connector 172, while anoutlet passage (not shown) is connected to a pair of flexible conduits174 with a connector 176.

[0058] As seen in FIG. 1C, the pressure of the fuel supplied by the fuelpump 128 is regulated to be the fixed value by a high pressure regulator180 which dumps fuel back to the vapor separator 118 through a pressurerelief line 182 in which a fuel heat exchanger or cooler 184 isprovided. It is important to keep the fuel under the constant pressure.Because the fuel amounts are determined by changes of duration ofinjection under the condition that the pressure for injection is alwaysthe same.

[0059] As seen in FIGS. 2 and 3, the flexible conduits 174 are connectedto fuel supply rails 186 with connectors 185. The fuel supply rails 186are made of metal so as to be rigid. The fuel supply rails 186communicate with the flexible conduits 174 and also fuel injectors 102when they are held on the fuel supply rails 186.

[0060] The respective fuel rails 186 are affixed to both of the maincylinder head members 74 at bosses 188 with positioning bolts 190.Apertures 191 are provided on the fuel rails 186 for the positioningbolts 190 passing through the apertures 191. The fuel injectors 102 areheld between the fuel supply rails 186 and the cylinder head members 74.Mount sections 192 of the fuel injectors 102 are inserted into bosses194 so as to be exposed to combustion chambers. Flange portions 196 ofthe fuel injectors 102 are supported with forked members 198 that areaffixed to the cylinder head member 74 at bosses 200 with bolts 202. Theflange portion 196 on each fuel injector 102 extends about the fuelinjector 102, generally surrounding the injector nozzle (although thenozzle is spaced from flange portion along a longitudinal axis of theinjector body). In the illustrated embodiment, the flange portiongenerally encircles the injector nozzle. The bosses 200 can be replacedby other positioning constructions. An additional construction is shownin FIG. 8 and will be described later.

[0061] The forked member 198 is made of anti-corrosive metal such asstainless steel and aluminum or synthetic resin. In this manner, theforked member 198 is prevented from corroding and deteriorating, andmaintains its shape and integrity in order to apply a generally constantloading on the fuel injector. The fuel injector mounting constructionand loading will be described in more detail below.

[0062] Although the same bosses 188, 194, 200 are provided on thecylinder head member 74 of the other bank 58, they are simplyschematically shown in FIG. 3 for avoiding redundancy. The high pressurefuel pump 128, pump drive unit 132, inlet and outlet module 170,flexible conduits 174, fuel rails 186 and fuel injectors 102 are unifiedtogether. These unified components form a high pressure fuel injectionassembly 206. The affixing construction including the mounting structureof the fuel injector 102 will be described more in detail with referenceto FIGS. 8, 9 and 10 later.

[0063] Fuel is supplied from the high pressure fuel pump 128 to theflexible fuel conduits 174. The fuel conduits 174, in turn, deliver fuelto a pair of vertically extending fuel rails 186. The fuel rails 186,then, supply fuel to the fuel injectors 102.

[0064] As seen in FIG. 1B, after the fuel charge has been formed in thecombustion chambers by the injection of fuel from the fuel injectors102, the charge is fired by firing the spark plugs 98. The injectiontiming and duration, as well as the control for the timing of firing ofthe spark plugs 98, are controlled by the ECU 96.

[0065] Once the charge burns and expands, the pistons 62 will be drivendownwardly in the cylinder bores 60 until the pistons 62 reach thelowermost position. At this time, an exhaust port (not shown) will beuncovered so as to open the communication with an exhaust passage 204formed in the cylinder block 56. The exhaust gasses flow through theexhaust passages 204 to manifold collector sections 206 of respectiveexhaust manifolds that are formed within the cylinder block 56. Theseexhaust manifold collector sections 206 communicate with exhaustpassages formed in an exhaust guide plate 42 on which the engine 36 ismounted.

[0066] A pair of exhaust pipes 208 depend from the exhaust guide plate42 and extends the exhaust passages 204 into an expansion chamber 210formed in the driveshaft housing 32. From this expansion chamber 210,the exhaust gasses are discharged to the atmosphere through a suitableexhaust system. As is well known in outboard motor practice, this mayinclude an underwater, high speed exhaust gas discharge and an above thewater, low speed exhaust gas discharge. Since these types of systems arewell known in the art, a further description of them is not believed tobe necessary to permit those skilled in the art to practice theinvention.

[0067] A feedback control system, indicated generally by the referencenumeral 214 is provided for realizing a control strategy along which theinitiation and duration of fuel injection from the fuel injector 102 andtiming of firing of the spark plugs 98 are controlled. The feedbackcontrol system 214 comprises the ECU 96 and a number of sensors whichsense either engine running conditions, ambient conditions or conditionsof the outboard motor 30 that will effect engine performance. Certain ofthe sensors are shown schematically in FIG. 1 and will be described byreference to that figure.

[0068] There is provided, associated with the crankshaft 54, acrankshaft angle position sensor 216 which, when measuring crankshaftangle versus time, outputs a crankshaft rotational speed signal orengine speed signal indicated schematically at 218 to the ECU 96.

[0069] Operator demand or engine load, as determined by throttle angleof the throttle valve 90, is sensed by a throttle position sensor 220which outputs a throttle position or load signal 222 to the ECU 96. Whenthe operator desires to gather speed, i.e., accelerate the engine speed,a throttle on a steering handle (not shown) is operated by the operator.The throttle valve 90 is, then, going to open toward the certain openposition that corresponds to the desired speed at which air charge isinduced more than before into the crankcase chamber 68 through thethrottle bodies 88. Also, the engine load increases, for example, whenthe associated watercraft advances against wind. In this situation, theoperator also operates the throttle so as to recover the speed that maybe lost.

[0070] A combustion condition or oxygen (02) sensor 224 is provided thatsenses the in cylinder combustion conditions by sensing the residualamount of oxygen in the combustion products at a time near the time whenthe exhaust port is opened. This output and air fuel ratio signal isindicted schematically at 226 to the ECU 96.

[0071] There is also provided a pressure sensor 228 in line connected tothe pressure regulator 180. This pressure sensor 228 outputs the highpressure fuel signal to the ECU 96, which signal line is omitted in FIG.1.

[0072] There also may be provided a water temperature sensor 230 (seethe lower right-hand view) which outputs a cooling water temperaturesignal 232 to the ECU 96.

[0073] Further, an intake air temperature sensor 234 (see the upperview) is provided and this sensor 234 outputs an intake air temperaturesignal 236 to the ECU 96.

[0074] Although these are all sensors shown in FIG. 1, it is, of course,practicable to provide other sensors such as an engine height sensor, atrim angle sensor, a knock sensor, a neutral sensor, a watercraft pitchsensor and an atmospheric temperature sensor in accordance with variouscontrol strategies.

[0075] The ECU 96, as has been noted, outputs signals to the fuelinjectors 102, spark plugs 75, the lubrication pumps 94 and the highpressure electric fuel pump 124 for their respective control. Thesecontrol signals are indicated schematically in FIG. 1 at 238, 240, 242and 244, respectively.

[0076] In addition (see FIG. 2), a starter motor 246 for starting theengine 36, a tensioner 248 for giving tension to the belt 166, aflywheel 250 and a cover member 252 for covering the rotating componentssuch as the high pressure fuel pump 128 are provided.

[0077] The outboard motor 30 has an engine cooling system. Withreference to FIGS. 4 through 8, primarily the cooling system will now bedescribed below. The mounting structure of the fuel injector 102 will bepartly included in the following descriptions.

[0078] The engine cooling system is generally indicated with thereference numeral 254. Actually, the main cylinder head member 74 of thecylinder head assembly 72 is affixed to the cylinder block 56 via agasket 256 (see FIG. 7). The main cylinder head member 74 has theaforenoted boss 194 for holding the mount section 192 of the fuelinjector 102 (see FIG. 8). The axis of the boss 194 has a certain anglerelative to the cylinder bore axis 258 so that the fuel injector 102 isplaced slantwise relative to the axis 258. Injection nozzles 260 of thefuel injectors 102 are exposed to the combustion chambers 78 throughopenings 262 formed at the bottom of the recess in the bosses 194. Theinjection nozzles 260 have a single or a plurality of injectionapertures. The fuel injector 102 and the spark plug 98 are adjoined eachother.

[0079] A gasket 264 is provided between the main cylinder head member 74and the cylinder head cover member 80. The cylinder head cover member80, main cylinder head member 74 and cylinder block 56 are securelyconnected with connecting bolts (not shown) in a known manner.

[0080] As schematically shown in FIG. 7, a cooling jacket 266 is formedcircumferentially around the cylinder bore 60. Another cooling jacket orcylinder head upstream jacket 268 is also formed circumferentiallyaround the recess 76 of the main cylinder head member 74. Also,generally around the bosses 101 for the spark plug 98 and at peripheryof the bosses 194 for the fuel injector 102 in the cylinder head member74, still another cooling jacket or cylinder head downstream jacket 270is formed. Further, the cylinder head cover member 80 also has a coolingjacket 271 (see FIG. 7). This cooling jacket 271 does not appear in FIG.8.

[0081] The gasket 256 has upper communication apertures 272 at itsalmost uppermost portion (see FIGS. 4 and 7) so as to allow waterflowing into the cylinder head upstream jacket 268 from the cylinderblock cooling jacket 266. Cavities 276 are located in the upstreamjacket 268 (see FIGS. 6 and 8) and in the close proximity to the bosses194 for the mount sections 192 of the fuel injectors 102. That is, thecavities 276 are formed deeper than the other part of the cylinder headupstream jacket 268. Because of this, cooling water is permitted toapproach closer to the mount sections 192 of the fuel injectors 102.

[0082] Lower communication apertures 278 are provided at the almostlowermost portion of the main cylinder head member 74 to discharge thewater from the cylinder head upstream jacket 268 and then supply it tothe downstream jacket 270. Middle communication apertures 280 areprovided between the upper cylinder UC and the middle cylinder MC andalso between the middle cylinder MC and the lower cylinder LC forallowing water, again, to flow from the upstream jacket 268 to thedownstream jacket 270.

[0083] Bypasses 282 are provided at the respective cylinders UC, MC andLC for further cooling the respective fuel injectors 102. As best seenin FIGS. 5 and 6, the bypasses 282 are placed directly under the fuelinjector bosses 194 and allow water to flow from the downstream jacket270 to the other water passage 229. The water flowing through thesebypasses 282 can take heat away from the main cylinder head member 74around the bypasses 282, which includes the fuel injector bosses 194.

[0084] The water flow in this cooling system 254 will be again describedmore in detail with reference to FIG. 7. Water is introduced into thecooling system 254 from the body of water surrounding the outboard motor30 by means of a water pump 290. Some amounts of this water is used forcooling the exhaust system and the reminder of the water is supplied tothe cylinder block cooling jacket 266 for cooling the cylinder block 56(the respective cylinders UC, MC and LC). Next, the water goes into thecylinder head upstream jacket 268 through the upper communicationapertures 272. Primarily, the water is then flow into the downstreamjacket 270 through the lower communication apertures 278. However,additionally, some of the water goes into the downstream jacket 270 enroute through middle communication apertures 280. The water flow in thecylinder head upstream jacket 268 and the downstream jacket 270 coolsthe body of the main cylinder head member 74.

[0085] Further, in this embodiment, the water in the upstream jacket 268goes into the downstream jacket 270 through the bypasses 282 Duringflowing through these bypasses 282, the water expedites the coolingeffect of the fuel injector bosses 194 and eventually the cooling effectof the fuel injectors 102.

[0086] The water, then, goes to a thermostat compartment 292 wherein aconventional thermostat is placed. After passing through the thermostatcompartment 292, the water goes to the water jacket 271 in the cylinderhead cover member 80 for cooling this portion and finally is dischargedto the body of water outside of the outboard motor 30.

[0087] As described above, because the cylinder head upstream jacket268, downstream jacket 270, cavities 276 and bypass passages 282 areprovided in this cooling system 254, the fuel injectors 102 and sparkplugs 98 are effectively cooled down as well as the cylinder headassembly 72. In addition, the bolt 202 is positioned at an generallyopposite place of the spark plug 98 relative to the fuel injector 102.Accordingly, the bolt 202 will not prevent cooling water from flowingsmoothly in such an limited narrow space.

[0088] The mounting construction of the fuel injectors 102 will now bedescribed in detail with reference to FIGS. 8 through 12. Although aplurality of fuel injectors 102 are mounted for multiple cylinders ofthe engine 36 in this embodiment, one fuel injector 102 will representthe other injectors because the same structure can be applied for them.

[0089] As described above, the forked member 198 is used for securingthe fuel injector 102 onto the main cylinder head member 74 and furtherfor exerting a loading or thrust force upon the fuel injector 102 towardthe combustion chamber 78. Thus, the forked member functions as a thrustmember. As best seen in FIGS. 11(A) to (C), the forked member 198generally has two sections: a fixing section 294 and a forked or thrustsection 295. The forked section 295 is formed with thrust portions 296and an intermediate portion 298. In the illustrated embodiment, thefixing section 294 has convex surfaces 299, which curvature is R1, onboth sides. The thrust portions 296 also have convex surfaces 300, whichcurvature is R2, at least on the side contacting the flange 196. Theintermediate portion 298 has concave surfaces unlike the fixing section294 and the thrust portion 296. As understood from FIGS. 11B and 11C,the fixing portion 294 is curved in a lateral direction, while thethrust portions 296 are curved in a longitudinal direction. This allowsthe forked member 198 to roll and pitch relative to the fuel injectorflange 196 and the mounting surface of the cylinder head member 74 whenassembled, as noted below.

[0090] The fixing section 294 has a bolt hole 301 which allows thefixing section 294 to pivot or yaw for position adjustment relative tothe fuel injector 102, as described below. The bolt 202 is a specialbolt as shown in FIG. 12 and used for affixing the forked member 198 tothe cylinder head member 74 as a fixing member. That is, the bolt 202has a protrusion 306 which has a generally partial spherical surface atits periphery and under its head portion 308. The fixing section 294has, therefore, a generally partial spherical recess 310 around the bolthole 300 to receive the spherical protrusion 306.

[0091] The main cylinder head member 74 has a relatively shallow hollowportion 312. Because the fixing section 294 is projected from theintermediate portion 298, the forked member 198 can be positioned at thehollow 312 and registered with a projected surface 299. That is, theforked member 198 can be temporarily placed and aligned on the cylinderhead member 74 before it is fixed to the cylinder head member 74 for theaccurate positioning.

[0092] The mount section 192 of the fuel injector 102 is formed betweenthe flange 196 and the injection nozzle 260. This mount section 192 hasa diameter larger than a diameter of the injection nozzle 260 butsmaller than a diameter of the flange 196. An opening 316, of a diameterlarger than a diameter of the nozzle opening 262, is formed at the boss194 in the cylinder head member 74 so that these openings 262, 316 aresections of a single opening. A step portion 318 occurs at thetransition between the large opening 316 and the small opening 262. Themount section 192 of the fuel injector 102 is seated at this stepportion 318. A disc spring 320 is provided between the mount section 192and the step portion 318 to seal up this area.

[0093] The flange 196 has a surface 321 at which the thrust portions 296of the forked member 198 contact. The surface 321 is generally flat.

[0094] The forked member 198 is affixed to the cylinder head member 74with the bolt 202. The forked section 295 receives the fuel injector 102between the thrust portions 296. When the bolt 202 is fastened tight,the thrust portions 296 apply a force on the fuel injector flange 196 ina direction toward the combustion chamber 78. That is, the forked member198 acts as a leaf spring and loads the fuel injection in a directiontoward the step 318. In particular, the forked member 198 directlyexerts the thrust force or loading onto the contact surface 321 of theflange 196 with the thrust portions 296. This loading is also exertedupon the disc spring 320 so that the spring 320 is compressed and sealsthe area between the cylinder head member 74 and the fuel injector 102.

[0095] The forked member 198 applies a generally uniform loading aboutthe flange 196, and thus on the disc spring 320 despite manufacturingtolerances. In accordance with the embodiment of the present invention,the forked member 198 has the fixing section 294 and the forked section295, both of which have the convex surfaces 299, 300 with curvatures ofR1 and R2, respectively. These convex surfaces 299, 300 allow the forkedmember 198 to incline itself That is, the forked member 198 has a selfadjustment function in positioning that allows the forked member 198 toassume a variety of orientations relative to the cylinder head member 74so as to accommodate for manufacturing tolerances while still squarelyloading the fuel injection 102 relative to the step 318 (i.e., theapplied force is generally normal to the step 318). Accordingly, anydistorted or non-uniform loading on the disc spring 320 can be avoidedand hence the sealing effect by the disc spring 320 can be uniform. As aresult, gasses leak and carbon deposits on the injection nozzle 260 areinhibited.

[0096] The self-orienting feature can also be accomplishes by formingthe convex surface of the cylinder head member 74 with a curved surfacethat acts a fulcrum over which the fixing section 294 can pitch, rolland/or yaw in order to allow the fuel injector flange 196 to sitsquarely against the step 318 within the opening. In this variation, thecurved protrusion lies on the surface of the cylinder head within thehollow 312 with the mounting hole for the bolt 202 being positionedgenerally at the center of the curved protrusion. The curved protrusionpreferably has a radius of curvature R1. This construction thus can beused with a forked member 198 having a flat fixing section 294 andconvex thrust portions 296.

[0097] Preferably both mounting constructions would also include thecombination of the spherical bolt protrusion 306 and the sphericalrecess in the forked member 198. This allows the forked member 198 to befixed to the cylinder head member 74 without imparting a significantforce in an oblique or parallel direction relative to the step 318.

[0098] In addition, the combination of the spherical protrusion 306 ofthe bolt 202 with the spherical recess 310 also inhibits unintentionalloosing of the bolt 202. This is particularly useful for the forkedmember 198. That is, due to the curved configuration of the forkedmember 198, the bolt 202 can loosen. However, because of the combinationof the spherical protrusion 306 and the spherical recess 310, thelooseness of the bolt 202 can be inhibited. It should be noted that theprotrusion 306 having the partial spherical surface and the sameconfigured recess 310 of the forked member 198 is dispensable if thebolt 202 would not loosen, for instance, if other types of lockingmechanisms are used (e.g., a lock washer).

[0099] The fuel injector 102 has its own axis, while the bolt 202 hasalso its own axis. After being affixed, both of the axes extend parallelrelative to each other. Also, the contact surface 321 of the flange 196and chord lengths across the ends of the convex surfaces 299 of theforked member 198 extend generally normal to the axes.

[0100] With reference to FIGS. 13 and 14, another arrangement fortemporarily supporting the forked member 198 will be described. The samemembers already described by reference to FIGS. 1 through 12 will beassigned with the same reference numerals and not described again foravoiding redundancy. Additionally, these same members will also beascribed the same reference numerals in connection with the descriptionof the embodiments illustrated in FIGS. 15 and 16. The above descriptionof these members, which are common among the embodiments, thereforeapplies equally to all embodiments unless indicated otherwise.

[0101] In this arrangement, pins 330 are connected to the cylinder headmember 74 and act as projections at respective positions on the maincylinder head member 74. The pins 330 can temporarily support the forkedmembers 198 instead of the hollows 312 shown in FIG. 8.

[0102] With reference to FIG. 15, still another arrangement fortemporarily supporting the forked member 198 will be described. In thisarrangement, the forked members 198 are unified with each other. Thatis, the respective forked members 198 are joined with the connectingsections 332.

[0103] The features of the present invention can be embodied in anengine other than the two stroke, crankcase compression engine asdescribed above. For instance, a four stroke engine such as an engine336 shown in FIG. 16 can employ the features. In this engine 336, a pumpdrive unit 338 is provided on the engine 336 and a pair of high pressurefuel pumps 340 are located at both sides of the pump drive unit 338. Apair of fuel supply rails 342 are provided and connected with the highpressure fuel pumps 340 with flexible conduits 344. Special componentsfor the four stroke engine 336 are, for example, an intake valve 346 anda camshaft 348.

[0104] The features and aspects of the present invention are applicablenot only to outboard motors but also to other engines for marinepropulsion systems such as stem drive systems, for land vehicles such asmotorcycles and automobiles, and for utility machines such as lawnmowers. Stationary engines can also employ them.

[0105] Although this invention has been described in terms of a certainpreferred embodiment, other embodiments apparent to those of ordinaryskill in the art are also within the scope of this invention.Accordingly, the scope of the invention is intended to be defined onlyby the claims that follow.

What is claimed is:
 1. A direct fuel injected, internal combustionengine comprising an engine body defining, at least in part, at leastone combustion chamber, a fuel injector arranged to spray fuel directlyinto the combustion chamber, the engine body having an opening throughwhich the fuel injector is inserted, the fuel injector having a contactsurface, a thrust member arranged to exert a loading onto the contactsurface toward the combustion chamber, a fixing member affixing thethrust member onto the engine body, a seal member disposed within aspace existing between the fuel injector and the opening, the thrustmember including a thrust section contacting the contact surface of thefuel injector and a fixing section at which the thrust member is affixedonto the engine body by the fixing member, and at least one of thethrust section and the fixing section having a convex surface.
 2. Adirect fuel injected, internal combustion engine as set forth in claim1, wherein the fuel injector and the fixing member have respective axesextend generally parallel to each other, and both the contact surfaceand a chord length of the convex surface extend generally normal to theaxes.
 3. A direct fuel injected, internal combustion engine as set forthin claim 2, wherein the fixing member has a generally partial sphericalsurface, the fixing section of the thrust member has a generally partialspherical recess, and the spherical surface of the fixing member isreceived at the spherical recess of the thrust member.
 4. A direct fuelinjected, internal combustion engine as set forth in claim 3, whereinthe fixing member is a bolt having a bolt head, and the sphericalsurface is formed at the periphery thereof and under the bolt head.
 5. Adirect fuel injected, internal combustion engine as set forth in claim1, wherein the opening in the engine body is formed with a smalldiameter section and a large diameter section to define a step portiontherebetween, and the seal member is disposed at the step portion.
 6. Adirect fuel injected, internal combustion engine as set forth in claim5, wherein the seal member is a disc spring.
 7. A direct fuel injected,internal combustion engine as set forth in claim 1, wherein the fixingsection of the thrust member has two sides, and both of the sides areconfigured as the convex surface.
 8. A direct fuel injected, internalcombustion engine as set forth in claim 1, wherein the thrust member isconfigured as a forked shape.
 9. A direct fuel injected, internalcombustion engine as set forth in claim 1, wherein the engine bodycomprises an engine block and a cylinder head, the engine block definingat least one cylinder bore in which a piston reciprocates, and thecylinder head is affixed to one end of the engine body and closes thecylinder bore, the cylinder head, together with the cylinder bore andpiston, define the combustion chamber.
 10. A direct fuel injected,internal combustion engine as set forth in claim 9, wherein the engineblock defining a plurality of the cylinder bores, a plurality of thefuel injectors are provided corresponding to the cylinder bores, aplurality of the thrust members are provided corresponding to the fuelinjectors, and the thrust members are unified with each other.
 11. Adirect fuel injected, internal combustion engine as set forth in claim9, wherein the thrust member has an intermediate section between thethrust section and the fixing section, and the cylinder head has ahollow portion at which the fixing section is nested.
 12. A direct fuelinjected, internal combustion engine as set forth in claim 9, whereinthe cylinder head has a projection, and the thrust member is positionedby registering the fixing section relative to the projection.
 13. Adirect fuel injected, internal combustion engine as set forth in claim9, wherein the cylinder head has a spark plug for firing the fuel and acoolant jacket disposed generally around the spark plug, the fuelinjector and the spark plug are adjacent each other, and the fixingmember lies on a side of the fuel injector generally opposite of thespark plug.
 14. A direct injected, internal combustion engine as setforth in claim 9, wherein the cylinder head has at least two coolantjackets, both of the coolant jackets are connected with each otherthrough a passage, and the passage is disposed in proximity to the fuelinjector.
 15. A direct injected, internal combustion engine as set forthin claim 9, wherein the engine additionally comprises an output shaftdriven by reciprocal movement of the piston, and a high pressure fuelpump is driven by the output shaft to supply pressurized fuel to thefuel injector.
 16. A direct injected, internal combustion engine as setforth in claim 1, wherein the engine includes a passage interconnectingthe combustion chamber with a crankcase chamber.
 17. A direct injected,internal combustion engine as set forth in claim 1, wherein the engineadditionally includes at least one exhaust valve regulating exhaust flowfrom the combustion chamber.
 18. A direct injected, internal combustionengine as set forth in claim 17, wherein the engine additionallyincludes at least one intake valve selectively opening to permit airflow into the combustion chamber.
 19. A direct injected, internalcombustion engine as set forth in claim 1 in combination with a marinepropulsion device, wherein the engine additionally comprises an outputshaft coupled to the marine propulsion device.
 20. A direct fuelinjected, internal combustion engine comprising an engine body defining,at least in part, at least one combustion chamber, a fuel injectorarranged to spray fuel directly into the combustion chamber, the enginebody having an opening through which the fuel injector is inserted, thefuel injector having a contact surface, a thrust member arranged toexert a loading onto the contact surface toward the combustion chamber,a fixing member affixing the thrust member onto the cylinder head, aseal member disposed within a space existing between the fuel injectorand the opening, the thrust member including a thrust section contactingthe contact surface of the fuel injector and a fixing section at whichthe thrust member is affixed onto the cylinder head by the fixingmember, and means for orienting the thrust member so as to produce agenerally uniform loading about the contact surface of the fuelinjector.